Cytological Studies in the Genus Leucaena Benth

Abstract

In twelve Leucaena taxa examined, the chromosome numbers were found to be n=26, 28 and 52. Six species and one subspecies have n=26, two species n=28 and three species n=52. Chromosome numbers in L. collinsii Britton and Rose (n=26), L. diversifolia (Schlecht.) Benth. ssp. diversifolia Pan et Brewbaker (n=52), L. pallida Britton and Rose (n=52) and L. retusa Benth. (n=28) were reported for the first time. The meiosis was regular in all the diploids and in most tetraploids. Multivalents were found in some tetraploids. The chromosome pairing in some species hybrids showed that species genomes in the genus Leucaena were very similar cytologically. Besides geographical and ecological isolation, polyploidy has played a very important role in the evolution of the genus.